Electronics Forum | Thu Mar 05 11:53:09 EST 2009 | dcell_1t
Hello to all. for certain time, we have been struggling with some issues on a PCB where have tombstoning on 0402 components (due to pad design) and dewetting in qfp256 0.5 mil pitch (discussed on another threads on this forum) component, we have pro
Electronics Forum | Wed Sep 18 06:53:05 EDT 2002 | CH
1) For solder short, pls check the paste height. Too much vol will cause short. For 15 mils use 5 mils thickness stencil if possible. Check profile preheat time to prevent hot slumpof the paste. 2) type 4 powder will be better for 15 mils pit
Electronics Forum | Thu Aug 22 22:19:13 EDT 2019 | sssamw
From the picture you present, it is a pin in paste part with pin length 2.2mm (a good length for 1.6mm PCB thickness), and seems the pin tilted and touch on PCB surface, thus causes up-part. Sorry I cannot image pin tilted not before placement but i
Electronics Forum | Fri Apr 20 08:41:56 EDT 2001 | jimlew
For those of you out there, like myself who are still using 2-d to measure paste ht, I have 2 questions. 1. Typically, what tolerance are you applying to your ht? +- 1 mil, or what? 2. Are you using metal squeegees, and if so, have you found that squ
Electronics Forum | Fri Mar 06 10:46:35 EST 2009 | davef
First, we agree with Loco that your QFP is nonwetting, rather than dewetting. Your sceen-shots look like ol' timey SnPb paste recipes. Turn-up the heaterometer dial. Second, on nitrogen: * We kinda think your O2 needs to be around 100ppm with 99.99%
Electronics Forum | Wed Sep 18 12:35:56 EDT 2002 | stepheno
Fourth - > back to design of PCB. Are there solder dams of > mask between the pads? If yes, that helps. If > not, pay close attention to stencil aperture > width and be sure that the aperture deposits less > paste by 1-2 mils per pad, centered o
Electronics Forum | Sun Nov 07 10:54:21 EST 1999 | Steve Thomas
We're looking at redesigning our stencils to facilitate better (well, it's pretty much non-existant, so any improvement is a big leap) release from fine pitch apertures. Currently we have perpendicular walled laser cut apertures. We'll be having
Electronics Forum | Wed Sep 18 18:41:17 EDT 2002 | davef
People have made good comments. Additional points are: * Your bridging is probably being caused by one or more of the following: [1] printing too much paste, [2] smearing the paste during placement or subsequent handling, or [3] paste slump during t
Electronics Forum | Thu Oct 17 17:18:48 EDT 2002 | Leandro G. Barajas
Hi everybody, This is a simple posting to initiate a discussion on different ways to troubleshoot, improve, and control the Stencil Printing Process SPP in SMT manufacturing. There are many SPC, ANOVA and other analysis techniques that provide insi
Electronics Forum | Mon Nov 20 21:02:46 EST 2000 | Michael Psrker
First question I have for you is: Are you assuming that standard precautions are in place at your facility to minimize moisture content i.e. air- deionizers, vacuum sealed packaging, humidity control in storage and manufacturing? You do not mention
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